TPR drain pipe length

Hello everyone. Just finished the Plumbing course. Just a question on the length of the drain pipe and when it is worth calling out. I looked at one that was just an inch or two short as far as terminating no more than 6” above the floor. If it was a foot or two short or missing altogether I would of course call it out. Just curious if a small discrepancy like this is still worth mentioning or not. Trying to get a sense of what is major enough to call out.

Thanks everyone. Sorry for the noob question.

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that would not be mentioned in my report…


Thanks James,

That’s what I was thinking too. Never hurts to ask though.

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Also, check to make sure 6" is the code in your area. In my area it has been amended to 18".

Still 6” in my area.

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The same around here…6"

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I wonder how many other areas allow more than 6" and I wonder the reasoning for it being increased here. :man_shrugging:

Next time I run into a plumber I’ll have to ask.

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If it’s right it’s right if it’s wrong it’s wrong. What if somebody gets hurt during the valve discharge and you inspected it knowing it was not installed correctly.


I seem to remember there being some argument/confusion/conflicting information regarding the wording of this Minnesota Rule. The 18 inches is in relation to the 12 inch pedestal/platform in garages. Add the 6 inch requirement to the 12 garage requirement and you have the 18 inch Rule. I would have thought the verbiage would have been amended by now, but it’s only been about 4 months, and with Covid shutdowns, the Holidays, and Gov’t being what it is in MN, perhaps by next year it will be corrected.

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That’s interesting and the math adds up I guess. Are you sure it was changed just 4 months ago though? I will admit I am not an expert code researcher/reader but I also found reference to the 18" in the 2015 MN Mechanical Code.

The reason I initially researched this about a year ago when I was first starting, is that I very seldom saw the pipe brought to withing 6" in my area. And I just couldn’t help but think I was missing something.

Does Minnesota currently use the 2018 IRC for residential with amendments? What does this publication say about the water heater relief valve discharge piping in a residence?

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Yes, it uses 2018 IRC. Under plumbing it just says what’s in the picture below. And chapter 4714 is what I posted a few posts above in post 4. Like I said, I’m no code research pro but this is all I can find.

That’s a very good point Martin. Thanks. I will try to think in those terms in the future.

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This is an area where significant local practice differences exist.
In my area for example TPR pipes can go up, but must exit outdoors.

You need to know local practices. But you’re not the police, and your primary role is to find safety, longevity and operational problems. Things that will actually cause a problem for a new owner. 1" off on the pipe is unlikely to ever be noticed, and could cause a problem only if a future City inspector had a bug up their behind due to other serious issues with a failed inspection.

Minnesotans are very very special breed of folk! You just cannot help but do things different :sunglasses: :man_shrugging:

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